Fluid motor



April 24, 1962 H. c. sToLTz 3,030,927

FLUID MOTOR Filed Oct. 14, 1959 4 Sheets-Shea?l 1 L+ 7a A "v M Am/9@ 96 13o 32,351+ ma la@ INVENTOR. H eYbeYc C. LoPCL April 24, 1962 H. c. sToLTzv 3,030,927

l FLUID MOTOR Filed Oct. 14, 1959 4 Sheets-Sheet 2 April, 24, 1962 H. c. sToLTz 3,030,927

FLUID MOTOR Filed oct. 14, 1959 4 sheets-sheet s Aprll 24, 1962 H. c. sToLTz 3,030,927

FLUID MOTOR Filed oct. 14. 1959 4 sheets-sheet 4 United States Patent C 3,ll30,927 FLUID MOTR Herbert S. Stoltz, Palmyra, Ia., assigner to AMP Incorporated, Harrisburg, Pa. Filed Oct. 14, 1959, Ser. No. 846,3411 Claims. (Cl. 121-13) This invention relates to reciprocable fluid motors of Y the type adapted to be operated by compressed air or other compressed gas.

An object of the invention is to provide an improved air motor which is adapted -to operate at relatively high speeds. A further object is to provide an air motor having improved inlet and exhaust valve means which are opened and closed by the piston of the motor. A still further object is to provide an air motor having pistonoperated exhaust and inletvalve means in which rapid closing and opening of the valves is achieved to permit high speed operation of the motor.

These and other objects are achieved in a preferred embodiment, herein disclosed in conjunction with a terminal crimping tool, in which the piston of the air motor has an axially bored cylindrical extension projecting from one side thereof. The inlet and exhaust valves are mounted in the end wall of the cylinder of the motor and on the opposite side of the piston from the cylindrical extension. The inlet valve is provided with a spring which urges it toward its closed position, however, it is maintained in its open position at the start of a cycle of the air motor by means of a control rod which is coaxially mounted with respect to the piston and extends into the hollow interior of the projection. The exhaust valve is also mounted in the end wall of the cylinder and the control rod maintains the exhaust valve in its closed position at the beginning of the cycle. Means acting between the piston and the control rod cause the latter member to move out of engagement with the inlet and exhaust valves as the piston approaches the end of its power stroke so that the inlet valve closes and the exhaust valve opens to permit the return stroke of the air piston. As the end of this return stroke is approached, the means acting between the piston and the control rod causes the control rod to move axially into engagement with the valves thereby to close the exhaust valve and open the inlet valve for the start of the next cycle.

In the drawings:

FIGURE l is a perspective View of a crimping tool incorporating an air motor in accordance with the invention;

FIGURE 2 is a sectional View showing the air motor and the hydraulic system of the tool of FIGURE 1, the parts being shown in the positions they occupy at the beginning of a power stroke of the air motor;

FIGURES 3-6 are sectional views similar to FIGURE 2 but showing only the air motor in detail and illustrating the positions of the parts a-t different portions of the operating cycle;

FIGURE 7 is an enlarged view showing the inlet and exhaust valve means of the air -rnotor in accordance with the invention; and

FIGURE 8 is an exploded View of the control rod pressing tools of this type are, of course, adaptable to a variety of uses, such as rivet setting or pipe bending, and the invention is not necessarily limited to the crimping of electrical terminals.

Referring now to FIGURE 2, body portion 4 has a first internal bore 1i) which constitutes the cylinder for a hydraulic piston 8 from which the ram 6 extends. A somewhat smaller diameter bore l2 is provided in the upper portion of the tool body, as viewed in FIGURE 2, and a coil spring 9 surrounds the ram and acts between the end wall of bore l2 and the face of piston 8 normally to bias the piston and ram downwardly.

As is explained below, the interior of tool body 4 is employed as a reservoir for hydraulic iluid yand the hydraulic system of the tool is of the closed circuit type. It is therefore necessary to provide means to prevent cavitation in the reservoir as the ram and piston move upwardly. To this end, ram 6 provides a 'transverse bore lai which is sealed by spring biased plugs lo, the plugs being retained in the bore by a collar I9. Bore 14 is open to the `atmosphere through a passageway i7 and an axial bore iS which, in use, also receives the stem of a crimping die. p v

The lower end of cylinder lil is closed by means of a cylinder head 18 threaded into the cylinder and having an yaxially extending boss 20 which projects into a depression in piston 3. An axial bore 22 extends through cylinder head lil and is counterbored at each end 24, 26. A spring-biased ball check valve 28 is provided in counterbore 24 to prevent flow of hydraulic iluid from the cylinder lil on the lower side of piston S into axial bore 22. A passageway Sil extends obliquely from counterbore 26 and is enlarged at 32 for the accommodation ot' a springbiased ball check valve 3d which is held within this enlarged portion of the passageway by means of a threaded plug 35 having an axial opening extending therethrough. The oblique passageway 3l), 32 communicates with an annular chamber 36 defined by a reduced diameter lower end portion of cylinder head I8 and by the walls of the cylinder itself. This annular chamber communicates by means of passageways 3S, 4d, 4l with the reservoir on the upper side of piston 8.

On the underside of cylinder head 1S, there is provided a Ihollow cylindrical extension i2 kcoaxially disposed with respect to the cylinders 19,12. An air piston 44 slidably surrounds this extension and is -reciprocable within an air cylinder 46 which is in axial alignment with cylinder 1t). Piston 44 is normally biased downwardly by means of a coil spring 48 interposed between a ledge on the piston `and an inwardly extending lip 47 of the cylinder 46. Air is supplied to the interior of cylinder 46 by means of a line 51 coupled to the cylinder by means of a fitting 50.

A passageway 54 extends through cylinder head 18 near its rim and is counterbored at its upper end 56 for the accommodation of a spring-biased ball check valve 5S. A rod 52 in this passageway rests upon piston 44 and is moved upwardly upon admission of compressed air into cylinder 46 beneath piston 44. Such upward movement of the rod opens valve S8 and permits hydraulic fluid to ilow into passageway 54 fromwhence it will flow through a passageway 6@ and into annular chamber 36 to permit return of the hydraulic iiuid to the reservoir as is explained below.

The reciprccable air motor, generally indicated at 62, is mounted on the lower end of cylinder 46 and coaxially aligned with respect to the upper portions of the tool. This air motor comprises a cylinder 64 closed at its upper end by an air cylinder head 66 which is secured in the inwardly directed end portion of the head 2. Cornplace by means of a snap ring 67. This cylinder head has an enlarged central opening which is threaded at 68 into engagement with the lower end of cylindrical extension 42. Since the upper portion of cylinder 64 is not pressurized in use, it is desirable to provide a vent as shown at 70 to the atmosphere. The piston 72 of the air motor has an extension 74 on its upper side from the end of which extends a pump plunger 76. Upon reciprocation of the piston and the pump plunger, hydraulic uid is pumped from the reservoir in the upper portions of the cylinders 10, 12 to the lower portion of cylinder beneath the piston 8.

Extension 74 is axially hollow for a substantial portion of its length and is internally threaded to receive an axially bored and counterbored nut 78. A tubular control rod 80, extends through the central opening in nut 73 and provides an enlarged head 82 on its end. It will be apparent from the drawing that the diameter of the opening in extension 74 is such as to permit relative movement of head vS2 up to the end wall 33 of this opening. A stern 84 (see FIGURE 8) slidably received in rod 80 has an enlarged diameter end portion 86 and a conical tip portion 88, which portions function as a cam as explained below. Advantageously, a screw S9 is provided in the upper end of rod 30 to provide an adiustable stop. A pin 90 secured to and extending transversely of stern S4 projects through an elongated slot 92 in rod S0 to permit limited relative motion between the rod and the shank. The lower end of both the rod and the cylindrical and conical portions of 'the shank project into a bore 94 in the end wall 96 of cylinder 64. Bore 94 is counterbored and receives a bushing 98 having a uniform internal diameter in its lower portions which is substantially larger than the diameter of control rod S0 and flares as shown at 102 to provide a conical camming surface for purposes described below.

Rod S0 has a circumferential groove 104 on its lower end and slidably accommodates a collar 106. This collar has cylindrical lower end portion 107 which extends downwardly, when the parts are in positions of FIGURE 2, between the surface of the rod and the internal surface of the bushing, and an external conical surface 109. A plurality of ball bearings 108 are normally seated in groove 104 and are received in holes in the lower portion of the collar so that they bear against the surface of bushing 98. A spring 110, interposed between the surface of this collar and the under side of nut 73, urges collar 106 downwardly to the position of FIGURE 2. An additional coil spring 112 is positioned between the head 32 of the rod and nut 78 so as to normally bias the control rod 80 upwardly. Springs 110 and 112 should be of such relative strength that the parts will be in equilibrium in the position shown in FIGURE 2, Le., the spring 112 will not have sullcient strength to push the rod 80 upwardly beyond the position of FIGURE 2.

Air is admitted into the interior to the cylinder 64 on the lower side of piston 72 by means of an inlet passage 116 which communicates with a radially extending passageway 118 (FIGURE 7) having a counterbore 120. An inlet check valve 124 is provided in counterbore 120 and is normally biased to the closed position by means of a coil spring, although this valve is maintained in its open condition in FIGURE 2 by cylindrical portion 86 of the stem which function as a cam and bears against an extension or stem 126 on the inlet valve; This stem projects through an opening in axial alignment with bore 118. Air is supplied by means of an air line 125 through a fitting 122 to chamber 120.

An exhaust port 128 in end wall 96 communicates with a radially extending bore 130 in which are provided a pair of valve bushings 132, 134. These valve bushings define chambers 131, 133 which are separated by a constricted passageway 129 in which is disposed the enlarged center part of a valve spool 136 having substantially the same diameter as the constricted passageway. A stern 138 extends radially toward the axis of the motor from spool 136 through an opening 137 and bears against the surface 86 of the cam on the opposite side from the stem 126. Chamber 133 communicates with the atmosphere through an exhaust port 142. It will be appreciated that valve spool 136 is freely slidably rightwardly or leftwardly from the position shown in FIG- URE 2 although it is prevented from moving rightwardly by virtue of the presence of the cam 36. An additional stem 141 extends radially outwardly from valve spool 136 and has an end portion which is slidable in the bore of a closure plug. This stem maintains the stem 138 in alignment with opening 137.

Air lines 51, 144 are connected to a source of compressedair through a manually operated control valve 146 having a control plunger 148. Advantageously, this valve is constructed such that when the plunger is in its raised (i.e., normal) position, air is supplied to line 51 so that relief valve 58 in the hydraulic system is open. When the plunger is moved downwardly towards the valve body, compressed air is supplied through line 144 to the air motor only and not through line 51. Valve 146 is constructed such that line 51 is open to the atmosphere when the plunger is moved downwardly thereby to vent air from the under side of piston 44.

In use and assuming the parts are in the positions of FIGURE 2, the plunger of control valve 146 is depressed thereby to admit air through line 144 past the inlet valve and through passageway .116 to the under side of piston 72. When the under side of this piston is pressurized, compressed air will also pass through port 128 into chamber 131 and will bias valve spool 136 to the position shown in FIGURE 2 and thereby securely hold this exhaust valve closed. As the compresed air from the line drives piston 72 upwardly, control rod 80 at rst remains stationary as spring 112 is compressd and the upper end of nut 78 is brought into engagement with the under side of head 82 (FIGURE 3). Thereafter and upon further upward movement of the piston, rod is carried upwardly along with the piston. However, for a brief interval, stem 84 remains stationary by virtue of the lost motion pin slot connection 90, 92. During this same brief interval, ball bearings 108 are cammed outwardly and into the conical portion 102 of bushing 98. The mechanism of this outward camming of the ball bearings can be understood from a close inspection of FIGURE 3. As the rod 80 moves upwardly it tends to carry the ball bearings and collar 106 upwardly. However, spring 110 discourages, but does not prohibit, upward movement of the collar so that as the ball bearings enter the conical portion 102 of bushing 98, the upward force exerted on the rod causes the balls to be pushed radially into this conicalportion as shown in FIG- URE 3. When the ball bearings are displaced entirely out of groove 104 and are tangent to the surface of the control rod 80, this rod is free to move axially. At this time, the stored energy of spring 112 moves the rod rapidly upwardly relative to both the piston and to the cylinder itself (FIGURE 4). As rod 80 moves upwardly, it engages pin on stem 84 and thereby pulls this stem and the enlarged end portions 86, 88 upwardly. As the enlarged portion 86 moves upwardly relatively past stems 126, 138, these stems are free to move radially inwardly, the stem 126 being biased inwardly under the iniluence of spring 12S and the stem 133 being biased inwardly under the influence of the compressed air on the left-hand side of valve spool 136. The tendencey of these stems to move inwardly assists the upward movement of the conical cam portion 88 after the cylindrical portion 86 has moved relatively past the stems. In this manner a rapid and positive reversal or shifting of the valves 124, 136 is achieved; i.e., inlet valve 124 is closed and exhaust valve 136 is opened as their stems 126, 138 move radially inwardly.

At the time rod 80 is projected upwardly and the inlet and exhaust valves are closed and opened respectively, the piston reaches the end of its power stroke and begins to move downwardly under the inuence of spring 114.

As shown in FIGURE 4, at the instant of reversal of the direction of motion of piston 72, the adjusting screw 89 in the'end of the rod Sil bears against the end wall 83 of the'recess in projection 74 so that as the piston moves downwardly, it carries rod 80 downwardly. During this portion of the cycle, spring 114 overcomes spring 110 and compresses this spring as shown in FIGURE 5. Energy is stored in the spring 110 during this interval by reason of the fact that collar 106 cannot move downwardly because ofthe wedging effect of ball bearings 198. When the circumferential groove in the rod S9 reaches the ball bearings, these bearings are cammed into the groove by the spring `and the stored energy of the spring abruptly moves the control rod downwardly relative to the piston. FGURE 6 shows the positions of the parts immediately prior to the movement of the balls into groove 104. As the rod moves down, its head portions 86, 88 engage stems 126, 138, thereby to open the inlet valve and close the exhaust valve.

With each cycle of reciprocation of the air motor and thc pump plunger 76, oil is pumped from the upper side of piston 8 to the under side thereof and the ram 6 is driven upwardly. Since the hydraulic system in the tool body 4 is of the closed circuit type, it is necessary to prevent cavitation. When the ram 6 is in its lower position as shown in FIGURE 2, the plugs 16 are displaced radially inwardly as shown; however, as oil is progressively displaced from the upper side of piston 8 to the lower side thereof, these plugs move radially outwardly and occupy the volume in this reservoir which would otherwise be vacant.

A salient advantage of the invention is that very rapid shifting of the valves is achieved and this, in turn, permits a relatively high speed on the part of the air motor. The inlet valve is opened and the exhaust valve is closed at the end of the exhaust stroke during a single interval of time, and this interval itself is extremely short because of the fact that the control rod 84 is shifted very rapidly infboth directions. When the inlet valve is closed and the exhaust valve is opened at the end of the power stroke, the rod 84 is shifted rapidly because of the fact that the valves 124, 136 are being urged into the new positions that they will occupy. At the end of the exhaust stroke, shifting takes place very rapidly by virtue of the stored energy in spring 1li() which is stored until it is sufficient to very rapidly displace the entire control spindle and valve rod assembly downwardly. The control rod 84 and the springs thus constitute a spring loadable and triggerable means which acts between the piston and the valves to shift them at the end of each power stroke and again at the end of each exhaust stroke.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by Way of illustration only. The actual scope of the Y invention is intended to be defined in the following claims when viewed in their properperspective against the prior art.

I claim:

l. An air motor comprising, a pneumatic cylinder, a reciprocable piston in said cylinder, an inlet valve and an exhaust valve disposed on one side of said piston, said valves being movable radially towards and away from the axis of said cylinder, said inlet valve beingclosed and said exhaust valve being open when'said valves are moved radially inwardly towards the axis of said cylinder, said inlet valve being open and said exhaust valve being closed when said valves are moved radially outwardly away from said axis, slidable valve shifting means coaxially disposed with respect to said cylinder and engageable with said inlet and exhaust valves, and spring loadable and triggerable means acting between said piston and said valve shifting means to move said valve shifting means into engagement with said exhaust valves at the end of the exhaust stroke of said piston thereby to open said inlet valve and close said exhaust valve, and to move said valve shifting means out of engagement with said valves at the end of the power stroke of said piston thereby to close said inlet valve and open said exhaust valve.

2. An air motor comprising, a pneumatic cylinder, a reciprocable piston in said cylinder, an inlet valve and an exhaust valve disposed adjacent to said piston and on one side thereof, said valves being radially movable towards and away from the axis of said cylinder, said inlet valve being closed and said exhaust Valve being open when said valves are moved radially inwardly towards the axis of said cylinder, said inlet valve being open and said exhaust valve being closed when said valves are moved radially outwardly and away from said axis, a rod coaxially disposed with respect to said cylinder having camming means thereon engageable with said valves to maintain said valves outwardly from said axis, and spring means effective between said piston and said rod axially to shift said rod at the end of the power stroke of said piston and disengage said camming means from said valves and to shift said rod at the end of the exhaust stroke of said piston to engage said camming means with said valves.

3. An air motor comprising a pneumatic cylinder, a reciprocable piston in said cylinder, an inlet valve and an exhaust valve disposed adjacent to said piston and on one side thereof, said Valves being radially movable towards and away from the axis of said cylinder, said inlet valve being closed and said exhaust valve being open when said valves are moved radially inwardly towards the axis of said cylinder, said inlet valve being open and said exhaust valve being closed when said valves are moved radially outwardly and away from said axis, a slidable rod coaxially disposed with respect to said cylinder, valve camming means coaxially mounted with respect to said rod and having a lost motion connection therewith, a first spring acting between said rod and said piston and normally urging said rod away from said valves, a second spring acting between said rod and said piston and normally urging said rod towards said valves, means for neutralizing said second spring at the end of the power stroke and during the exhaust stroke of said piston whereby said iirst spring disengages said camming means from said valves, said second spring normally maintaining said rod and camming means in engagement with said valves during a substantial portion of the power stroke of said piston whereby, at the end of the power stroke of said piston, said iirst spring disengages said cam from said valves through said lost motion connection, and at the end of the exhaust stroke of said piston said second spring is effective to reengage said cam with said valves.

4. An air motor comprising a cylinder having a reciprocable piston therein, a control rod extending through said piston and coaxially disposed with respect thereto, said rod being movable relative to said piston, an end Wall on said cylinder having radially movable inlet and exhaust valves therein, said inlet valve lbeing closed and said exhaust valve being open whensaid valves are positioned radially inwardly of the axis of said cylinder, said inlet valve being open and said exhaust valve being closed when said valves are positioned radially outwardly of the axis of said cylinder, said valves being normally biased to their inward positions, valve camming means engageable With said Valves to maintain said valves in their out- Ward positions, said camming means having a lost motion connection with said rod, a first spring effective between said rod and said piston normally urging said rod and said camming means away from said valves, a second spring effective between said rod and said piston normally urging said rod and said camming means into engagement with said valves, said second spring being stronger than absage? said 'rst spring whereby said 'camming means is normally engaged with said valves, and means for neutralizing said second spring for a period extending from the end of the power stroke to the end of the exhaust stroke of said piston whereby said camming means is disengaged from said valves under the influence of said first spring and said valves are shifted at the end of the power stroke, and said cammiug means is engaged with said valves at the end of the exhaust stroke under the inuence of said second spring and said valves are again shifted.

5. A reciprocable air motor comprising, a pneumaatic cylinder having a trst end wall, a piston within said cylinder, a centrally hollow axial extension on said piston on the opposite direction from said end Wall, an inlet passageway for compressed air in said end wall and opening into said cylinder, a normally closed inlet valve in said passageway, an exhaust passageway in said end wall and an exhaust valve in said passageway, said exhust valve and said inlet valve having stem portions extending towards the axis of said cylinder, said inlet valve being closable upon movement towards the axis of said cylinder and said exhaust valve being openable upongmovement towards said taxis, slidable valve control means coaxially disposed in said cylinder, said valve control means being movable relatively past said stem portions to control said exhaust and inlet valves, and means acting between said piston and said valve control means for moving said valve control means out of engagement with said stems at the end of the power stroke of said piston andr for moving said valve control means into engagement with said stem portions at the end of the exhaust stroke of said piston. 

